Conventional sanitary units such as urinals employ a water seal to prevent odours and noxious gases from the waste system passing through the urinal outlet into the surrounding environment. Such sanitary units require flushing on a regular basis and particularly after use, to ensure the fluid which forms the barrier is clean and odour free.
However, the costs associated with flushing, particularly in the areas where water is scarce can be considerable. Therefore there has been a movement towards low and zero water usage urinals to reduce costs. The slow and zero water usage urinals use the liquid which is being disposed of down the sanitary unit (for example urine) to form the liquid seal. Where the disposed of liquid has a smell, for example in the case of urine, a one-way valve may be used alone or in conjunction with a deodorising block which masks the smell.
One-way valves in the form of rubber diaphragm type valves have proven to be quite successful. However, removal and replacement of a worn or blocked valve involves the operator/user, in some cases, having to at least partially dismantle the outlet and put their finger inside the outlet to pull the valve out. This is both an unpleasant and time-consuming operation.